2019/02/09

Shilka, the revolutionary nightmare

.

(I exhausted my supply into the recent link dump, so I had to dust off and tweak an old draft about hardware history to maintain the weekly schedule.)

The most influential move in Cold War air warfare was probably the introduction of the ZSU-23-4 'Shilka', as it changed air warfare from the late 60's to the late 80's in conjunction with the SA-6 "Gainful"/2K12 "Kub" battlefield area air defence missile.

I'll try to substantiate this claim, of course:

Soviet(-style) battlefield air defences were never particularly respected by German or later NATO air power until the introduction of the Shilka. The habit of Red Army troops to shoot at attacking aircraft with everything they got (that is, with all rifles) was meanwhile dangerous enough to largely prohibit ground attack mission profiles which required much air time below 300 metres altitude. The German WW2 battlefield air defences (mostly calibres 20 and 37 mm) were plenty and dangerous, but they didn't prevent punishing air strikes either (German troops used their machineguns, but rather rarely their rifles against aircraft).

ZSU-23-4 Shilka, three ZSU-57 in background

All this changed when there were finally plenty self-propelled anti-air guns (SPAAG) / Flakpanzer in service with a 3D radar and ballistics computer. The Soviets had introduced the Shilka with four 23 mm autocannons, search and fire control radar and fire control computer in the mid-60's and battlefield air defence potential made a huge leap forward. They did not upgrade their older twin 57 mm SPAAGs with at least a rangefinder radar to complement the Shilka with some longer effective range (nor did they produce their expensive twin 37 mm SPAAG design). Instead, the SA-6 was about to deal with anything flying too high for the Shilka, at least in theory (or even more theoretically, the SA-9).

Meanwhile, the new portable Redeye (American) and SA-7 (Soviet) man-portable missiles were easily
countered with flares and evasive manoeuvres (including exploiting the
sun) and didn't force much of a change in tactics themselves (the same applies to the SA-9).

The common air/ground mission profiles which gave strike aircraft a great bird's view on the battlefield, road or fixed target had become very dangerous, for the aircraft would typically be engaged by ZSU-23-4 or SA-6 at those altitudes.

The best choices for ground attack on a march column had been a combination of unguided rockets and cluster bombs, maybe even use of autocannons (the Hunter's four 30 mm cannons were particularly effective) - applied in a shallow dive. The Shilka still allowed for this, but only from a rather high altitude, with associated loss of accuracy and increase in dispersion. The attack with 'iron bombs' was similarly reduced in efficiency.

This could have been compensated for with an increased usage of guided munitions, of course; laser guided munitions, Walleye-like and Maverick-like munitions.

The reinforcement of the Shilka with the SA-6 after a few years reduced this possibility to a niche approach.

The Yom Kippur War showed the dilemma: Fly high and the SA-6 may kill you. Fly low and the Shilka may kill you. Fly very low and you're not going to see much, nor have much time between detecting targets and passing them. Otherwise very useful munitions such as unguided rocket pods were of marginal value at very low level and bombs had to be adapted, too.

The Shilkas were more numerous and mobile than the SA-6 radars, so the latter became the target of choice to crack this team. But what was possible on the Sinai peninsula would not necessarily succeed in Central Europe, against the numbers and training of the Warsaw Pact.

The problem was simply that WW3 - if conventional - was expected to last but weeks before all might be lost (similar to the Yom Kippur War), and air power absorbed by taking out battlefield air defences first would not help much.

Up to the late 60's the North German plains were a dream for strike aircraft, as they provide much simpler terrain in which attacking columns could quite easily be found and engaged. Meanwhile, Central and South Germany are rather hilly with many woodland hilltops and strings of buildings adjacent to roads. Many roads are furthermore in woodland and thus visible only from two directions (fore, aft) and straight above.

The arrival of Shilka meant that suddenly the hilly terrain became more favourable, as the hills made radar-based air defence much more difficult. SA-6 threats could be countered by going very low level for a few seconds, and Shilka search radars had an effective early warning range shorter than the line of sight to the surrounding hills; often too little for the full engagement sequence.

This then more favourable terrain was still the less favourable terrain of the early 60's, though: Air power had greatly lost in efficiency due to the Shilka (ceteris paribus).

The respect for the area air defence missile threat such as the SA-6 was high enough for NATO to not follow the guided munitions path fully, but only partially. The new Jaguar and Tornado strike aircraft designed for the 1980's European theatre of operations made use of almost no guided ground attack munitions, for example.

Instead, very low level flight including the use of terrain following radar became the big fashion, despite the fact that look down/shoot down Doppler pulse radars and matching missiles had been introduced during the 1970's already. The dominant ground attack profile proved to be awfully susceptible to modern fighters, and even worse: Any fighter escorts were pressed into roughly the same profile and thus inherently disadvantaged against modern defending fighters.

Some attack capabilities from convenient altitudes were maintained, though: The Yom Kippur War had also showed that the semi-stationary SA-6 batteries could not support ground forces with their protective umbrella during fast-moving campaigns. Armoured spearheads exploiting a 'breakthrough' would typically still be vulnerable, and there were never enough missile batteries on either side to protect the rear areas well (airfields, bridges, depots). NATO, for example, maintained a kind of SAM belt from the Austrian/Swiss border to the North Sea, with many rear locations protected only by fighters or low level defences.

NATO did ultimately bet on the ability to take out or suppress the vital radars of area air defence batteries with its anti-radar missiles: An approach initially invented during WW2 and introduced for good during the Vietnam War.

This didn't help much against modern SPAAGs, though; laser rangefinders soon potentially gave SPAAGs the ability to defend against low level attackers without any use of a radar. The second generation of portable very short range air defence missiles (famous Stinger and others, amongst them the very countermeasures-defying laser beam rider missiles) added to this.

As a result, NATO air attack doctrine went back to the 15,000+ ft (more than 4,500 m) attack altitude and began to make use of many guided munitions. The technological advance and large production runs allowed for some very cost-efficient guided munitions, especially cheapened laser guidance or satellite navigation guidance kits. Sensors (imaging infrared optics and modern imaging radar) allow modern strike aircraft to attack just as well form this altitude as earlier strike fighters were able to do from much lower ones with 'Mk1 Eyeball' sensors.

Without Shilka and to a lesser extent its successor and relatively few Western counterparts all this wouldn't have happened.

1970's strike fighters could have flown at a convenient altitude for spotting targets, diving and temporarily flying very low when a missile battery threat was detected. The modern strikefighter of the 1980's might have utilized an underbelly autocannon pod to easily take out anything but main battle tanks from a convenient altitude (maybe 2,000 metres) while circling the target area. Unguided rockets, Maverick-like anti-tank missiles and wind-correcting cluster bombs with timed release might have reigned and we would never have seen submunition pods such as JP233 or MW-1. The typical strike fighter might also have had a much larger wing area like the F-16XL, because there would have been few terrain following mission profiles in low altitude dense air (which create problems for low wing loading aircraft and thus led to relatively small wings). Area air defence batteries could have been engaged by triangulating their position and attacking them low and close, since they wouldn't have been protected against this kind of attack by SPAAGs.

Air and sea warfare are so very much dominated by technology despite the importance of skill, numbers, support and weather that a single technological progress is able to change the entire picture. In the case of Shilka, this progress was actually announced two decades earlier, when the combination of SPAAG with fire control radar and fire control computer (a search radar was still unnecessary due to lower aircraft speed) was first feasible and envisaged. The nuke-crazy 50's may have delayed the inevitable revolution by a few years.

The result was that the face of modern air attack was changed, as it had to adapt to the threat.*

*: Strangely, the loss in efficiency was not followed by a shift in budget
priorities; NATO had already given up the idea of countering Warsaw Pact
tank quantity in a symmetric arms race despite the German experiences
from WW2 which indicated that this was feasible with enough good arms. The result was that Western great power militaries have become dependent on aerospace superiority.

P.S.: I link a lot to Wikipedia, but don't mistake this as a link to sources. The links are meant for those readers who cannot remember the specific thing at the moment. I cover a wide range of topics and do not expect the majority of my readers to have a matching range of interests and knowledge, so I make the texts easier by adding these links.

The Warsaw Pact had the Su-24 with terrain-following radar long before the similar Tornado IDS arrived. AFAIK it was meant for strikes well past the battlefield and became much less survivable once F-15s arrived in Europe.

The WP close air support was rather focused on bombing from safe-enough altitude if (V)ShoRAD was present. The NATO forces had no proper air defence umbrella above 2...4 km depending on the corps because IHAWK was much less mobile than SA-6.

The Soviets developed their countermeasures to IHAWK (stand-off jamming, anti-radar missiles, anti-radar version of MiG-25).

HOT, TOW and Hellfire could typically not be used at more than 2 km distance because of detection, identification and line of sight issues. Shilka was effective at 2 km, so attack helicopters always depended on the shortcomings of the Shilka radar and its operators.

The Su-24 essentially emulated the earlier F-111. I'm not sure how much of a difference the F-15s would have made - AFAIK they would have operated from two airfields of known location (Bitburg and Soesterberg - the latter squadron eventually moving to Lakenheath) which would have been prime targets in the event of war breaking out.

I was rather referring to the technical side (and the bulk of F-15s would probably have arrived later on English airports).The look down/shoot down tech and look-down capable AEW&C made terrain following strike fighters appear kinda obsolete if deployed in quantity.The MiG-23 did this to Tornado IDS as well, but the MiG-23's look down capability was difficult to use to good effect. That radar was too complicated for a one-man crew and I doubt AA-10 was ever good in shoot down use - it has a poor reputation even in the easier mission profiles. The earlier AA-7 was clearly worse.

Yanks came out of GW1 shouting from the rooftops that no Apache was shot down. Amazing. Genius of design and operational utility at work. Far deadlier and more survivable than we dreamed. We dont need to be so concerned about ground fire. The Apache really is that good!!!!!

Shilka and it's successor also drove the development of autonomous and semi autonomous weapons for launch from aircraft from low altitude at standoff ranges that would put the launch aircraft out of range of SPAAGs. As far as I am aware, of the various initiatives, only Brimstone bore fruit and was used in its intended role in its original purely MMW format, ripple fired against at least one enemy vehicle column in Libya.

Maverick would have initially imposed a highly problematic attack profile on the attacking aircraft. The earliest, non scene magnifying daylight TV A model would have been a complete waste of time in Europe. Things are a bit better now as the seeker can be slaved to a targeting pod allowing lock on from extended range (visibility permitting) and the attack aircraft to not have to fly in a near dead straight line toward the target. It's still far from ideal for countering a massed armoured attack under a dense modern IADS though. Even the (now no longer produced) WCMD and its winged variant are really only useful in permissive air environments.